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Formation Design of Distributed Telescopes in Earth Orbit for Astrophysics Applications

JOURNAL OF SPACECRAFT AND ROCKETS 2019年第5期56卷 1462-1477页

作者： Koenig, Adam W. Macintosh, Bruce D'Amico, Simone Stanford Univ Dept Aeronaut & Astronaut 496 Lomita Mall Stanford CA 94305 USA Stanford Univ Dept Phys 382 Via Pueblo Stanford CA 94305 USA

This paper presents a new formation design that enables deployment of large distributed telescopes aligned with inertial targets in Earth orbit. To minimize propellant consumption, the proposed design uses a two-phase operations concept including observations and formation reconfigurations. During observations, a quasi-continuous control system negates the relative acceleration perpendicular to the line of sight, allowing the interspacecraft separation to passively drift. After each observation, a formation reconfiguration is performed to ensure proper alignment with the target at the start of the next observation. Absolute and relative orbits that minimize the total delta-v cost of a specified mission profile are derived in closed-form including effects of perturbations such as Earth oblateness. Additionally, a new stochastic model predictive control architecture is proposed that uses an optimal impulsive control algorithm to efficiently control the formation. The performance and value of the proposed formation design are demonstrated through high-fidelity simulations of a reference mission to image the exoplanet AEgir using a small starshade and telescope. The results of these simulations demonstrate both that the proposed formation design globally minimizes the delta-v cost of the mission and that the mission is feasible with current propulsion technologies.

关键词： Telescopes Earth Astrophysics Parabolic Trajectory Propellant Model Predictive control Propulsion Technology control algorithm control Systems Perigee

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Nonlinear Airfoil Limit Cycle Analysis Using Continuation Method and Filtered Impulse Function

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AIAA JOURNAL 2020年第5期58卷 1976-1991页

作者： Yu, Q. Damodaran, M. Khoo, B. C. Natl Univ Singapore Singapore 119077 Singapore Natl Univ Singapore Ctr Flight Sci Singapore 119077 Singapore Natl Univ Singapore Temasek Labs Singapore 119077 Singapore Dept Mech Engn Block EA9 Engn Dr 1 Singapore 117575 Singapore Temasek Labs T Lab Bldg5A Engn Dr 1 Singapore 117411 Singapore

In this study, an adaptive step size control algorithm incorporated in the continuation method (CM) is developed and combined with the filtered impulse function method based on aerostructural solvers and applied to two aeroelastic analysis tasks concerned with modes tracking and parameter variation. The nonlinear limit cycle oscillation (LCO) of a NACA0012 airfoil with control surface free-play behavior is considered to illustrate how this adaptive step can achieve a balance between the stability, accuracy, and efficiency in the modes crossing region in modes tracking, the flutter point region in modes tracking, and the detrimental LCO region in parameter variation. It is shown that the computation time for modes tracking using this approach can be reduced by more than 65% while achieving almost the same estimate of the flutter speed as when using a fixed step size. The study also addresses a few unique and important phenomena in parameter variation such as modes jumping in the LCO curve that occur frequently using this adaptive step size algorithm. Furthermore, a combination of the modes tracking results to provide an estimate for the restart point for the CM solver to overcome the occurrence of possible extraneous solutions or divergence is proposed. The results of flutter analysis for linear structural system and nonlinear LCO analysis are validated against the results from experiments and the classical Theodorsen theory. The effect of viscous damping on the occurrence of detrimental LCO phenomena is also discussed and compared with the corresponding nondamping cases.

关键词： Airfoil Aeroelastic Stability Viscous Damping Computational Structural Dynamics control algorithm Structural System CFD Simulation Airspeed Influence Coefficients Lift Coefficient

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FEED FORWARD NEURAL NETWORK BCI-BASED TRAJECTORY-controlLED LOWER-LIMB EXOSKELETON: A BIOMECHATRONICS APPROACH

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INTERNATIONAL JOURNAL OF ROBOTICS & AUTOMATION 2023年第6期38卷 430页

作者： Roy, Ganesh Bhatia, Dinesh Bhaumik, Subhasis IIEST Dept Aerosp Engn & Appl Mech Sibpur 711103 W Bengal India Cent Inst Technol Kokrajhar Dept Instrumentat Engn Kokrajhar 783370 Assam India North Eastern Hill Univ NEHU Dept Biomed Engn Shillong Meghalaya India IIEST Sibpur India

In recent years, the design of an assistive robot for mankind has become an important area to robotics and biomechatronics researchers. The design of such a device involves many issues, including gait biomechanics, mechanical architecture, control system design, selection of actuator, sensor details, power storage, etc. The present work dealt with all the issues carefully to develop a rehabilitative trajectory -controlled lower -limb exoskeleton (TCLLE) prototype. The TCLLE prototype has been developed and tested with three trajectory control algorithms. The control circuit is built around a microcontroller and a master controller environment. The instantaneous inverse kinematic model has been developed for the single and double support phases of the exoskeleton to determine the appropriate joint space configuration for the gait trajectory. The mean steady-state errors obtained between reference and joint space trajectories are 0.0331 degrees, -0.0667 degrees, and 0.9112 degrees for ankle, knee, and hip joints, respectively. Finally, a brain-computer interface (BCI) system using neural networks (NNs) for communicating with TCLLE has been addressed. Average classification accuracy of 91.6% has been obtained as the NN classifier performance during the triggering operation.

关键词： Biomechatronics lower-limb exoskeleton gait training control algorithm BCI

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Rapid Simulation of 3D Liquid Sloshing in the Lunar Soft-Landing Spacecraft

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AIAA JOURNAL 2019年第10期57卷 4504-4513页

作者： Yu, Qiang Wang, Tianshu Li, Zirui Tsinghua Univ Sch Aerosp Engn Beijing 100084 Peoples R China Wenzhou Univ Coll Mech & Elect Engn Wenzhou 325035 Zhejiang Peoples R China

Sloshing of liquid fuel has significant implications in the accurate control of the spacecraft. Rapid simulation of the force and moment exerted by liquid against the spacecraft is rather important for the dynamics and control of the spacecraft. Fast numerical simulation models, especially those capable of dealing with violent liquid sloshing in the lunar soft-landing spacecraft with fluid merging and splitting, are required for real-time control algorithms. For this purpose, a modified smoothed particle hydrodynamics method, namely, noninertial smoothed particle hydrodynamics (NI-SPH), is proposed. In this method, noninertial coordinate system is used to derive transient external excitations to liquid. Meanwhile, the linear and angular momentum theorems of the particle system are adopted to calculate the force and moment exerted by liquid against the spacecraft, which avoids the accuracy loss of the integration of pressures. Furthermore, parallelization based on OpenMP is used to speed up the simulation. To show the accuracy and efficiency, results from the NI-SPH method are compared with those obtained by traditional computational fluid dynamics software, for several 3D liquid sloshing cases.

关键词： Lunar Soft Landing Liquid Sloshing Spacecrafts Computational Fluid Dynamics Software Liquid Fuels control algorithm Potential Flow Arbitrary Lagrangian Eulerian Number of Particles Coefficient of Viscosity

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Dependence of the compensation error on the error of a sensor and corrector in an adaptive optics phase-conjugating system

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QUANTUM ELECTRONICS 2015年第8期45卷 736-742页

作者： Kiyko, V. V. Kislov, V. I. Ofitserov, E. N. Russian Acad Sci AM Prokhorov Gen Phys Inst Moscow 119991 Russia ITMO Univ St Petersburg 197101 Russia

In the framework of a statistical model of an adaptive optics system (AOS) of phase conjugation, three algorithms based on an integrated mathematical approach are considered, each of them intended for minimisation of one of the following characteristics: the sensor error (in the case of an ideal corrector), the corrector error (in the case of ideal measurements) and the compensation error (with regard to discreteness and measurement noises and to incompleteness of a system of response functions of the corrector actuators). Functional and statistical relationships between the algorithms are studied and a relation is derived to ensure calculation of the mean-square compensation error as a function of the errors of the sensor and corrector with an accuracy better than 10 %. Because in adjusting the AOS parameters, it is reasonable to proceed from the equality of the sensor and corrector errors, in the case the Hartmann sensor is used as a wavefront sensor, the required number of actuators in the absence of the noise component in the sensor error turns out 1.5 - 2.5 times less than the number of counts, and that difference grows with increasing measurement noise.

关键词： adaptive optics system phase conjugation deformable mirror control algorithm sensor error corrector error compensation error matching of the number of counts to the number of actuators

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Oscillating U-Shaped Body for Underwater Piezoelectric Energy Harvester Power Optimization

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MICROMACHINES 2019年第11期10卷 737-737页

作者： Aramendia, Inigo Saenz-Aguirre, Aitor Boyano, Ana Fernandez-Gamiz, Unai Zulueta, Ekaitz Univ Basque Country Nucl Engn & Fluid Mech Dept UPV EHU Vitoria 01006 Spain Univ Basque Country Automat Control & Syst Engn Dept UPV EHU Vitoria 01006 Spain Univ Basque Country Mech Engn Dept UPV EHU Vitoria 01006 Spain

Vibration energy harvesting (VeH) techniques by means of intentionally designed mechanisms have been used in the last decade for frequency bandwidth improvement under excitation for adequately high-vibration amplitudes. Oil, gas, and water are vital resources that are usually transported by extensive pipe networks. Therefore, wireless self-powered sensors are a sustainable choice to monitor in-pipe system applications. The mechanism, which is intended for water pipes with diameters of 2-5 inches, contains a piezoelectric beam assembled to the oscillating body. A novel U-shaped geometry of an underwater energy harvester has been designed and implemented. Then, the results have been compared with the traditional circular cylinder shape. At first, a numerical study has been carried at Reynolds numbers Re = 3000, 6000, 9000, and 12,000 in order to capture as much as kinetic energy from the water flow. Consequently, unsteady Reynolds Averaged Navier-Stokes (URANS)-based simulations are carried out to investigate the dynamic forces under different conditions. In addition, an Adaptive Differential Evolution (JADE) multivariable optimization algorithm has been implemented for the optimal design of the harvester and the maximization of the power extracted from it. The results show that the U-shaped geometry can extract more power from the kinetic energy of the fluid than the traditional circular cylinder harvester under the same conditions.

关键词： energy harvesting piezoelectric pipelines underwater networks wireless sensor networks control algorithm

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Development of an Intelligent Power Management System for Solar PV-Wind-Battery-Fuel-Cell Integrated System

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FRONTIERS IN ENERGY RESEARCH 2021年 9卷

作者： Ani, Vincent Anayochukwu Univ Nigeria Nsukka UNN Dept Elect Engn Nsukka Nigeria

The objective of this work is to develop a power management system that will control the power flow of an integrated renewable energy system with the focus on solar energy and wind energy and dual energy storage systems (batteries are used as the primary energy storage system for short to moderate storage term, whereas hydrogen fuel cell is used as a backup and long-term energy storage). These storage systems are needed to provide high reliability and control systems are necessary for the stable and optimal operation of the whole system. An Intelligent Power Management System (IPMS) is developed to handle various changes in power supply and power demand by managing erratic power and provide suitable control algorithm for the whole system. In order to test and validate the proposed IPMS model, simulations were conducted under various power supply and power demand using power system modeled in HOMER environment. The performed simulations confirm the ability of the IPMS to satisfy the load at all times using solar and wind power (which are unsteady renewables), through the support of batteries and hydrogen fuel cell without a reduction in the power quality or load supply.

关键词： power management system hybrid system optimization control algorithm fuel cell renewable system integrated system

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Initial titration for people with type 1 diabetes using an artificial pancreas

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IFAC-PapersOnLine 2021年第15期54卷 484-489页

作者： Maria Sejersen Dimitri Boiroux Sarah Ellinor Engell Tobias Kasper Skovborg Ritschel Asbjørn Thode Reenberg John Bagterp Jørgensen Department of Applied Mathematics and Computer Science Technical University of Denmark DK-2800 Kgs. Lyngby Denmark

For people with type 1 diabetes and some with type 2 diabetes, the problem of insulin titration, i.e. finding an adequate basal rate of insulin, is a complex and time-consuming task. This paper proposes a simple model-free algorithm and a procedure for fast initial titration in people with type 1 diabetes (T1D). A modified proportional-integral-derivative (PID) controller (i) updates the estimated insulin basal rate, and (ii) administers micro-boli of insulin every 5 minutes using glucose measurements from a continuous glucose monitor (CGM). A bolus calculator mitigates the effect of meals and reduces postprandial peaks. We evaluate the performance of our system qualitatively and numerically using a virtual clinic of 1,000 T1D patients with a broad inter-patient variability representative of a real population of people with T1D. We let the titration phase run for three consecutive days, followed by a three-day test phase using the newly computed basal insulin infusion rate. The proposed algorithm is able to provide a safe titration and individualized treatment for people with T1D.

关键词： control algorithm PID Feed-forward control Run-to-run control Diabetes Artificial pancreas

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Assessment of SMA Electrical Resistance Change during Cyclic Stretching with Small Elongation

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SENSORS 2021年第20期21卷 6804页

作者： SLawski, Sebastian Kciuk, Marek Klein, Wojciech Silesian Tech Univ Dept Theoret & Appl Mech Konarskiego 18A PL-44100 Gliwice Poland Silesian Tech Univ Dept Mechatron Akad 2A PL-44100 Gliwice Poland

In this article, changes in NiTi alloy (Flexinol) electrical resistance during cyclic stretching with small elongation were investigated. A dedicated test stand consisting of motorized vertical test stand, force gauge, and electric resistance measuring device with an accuracy of 0.006 omega was developed. A dedicated control algorithm was developed using LabVIEW software. Changes in electrical resistance were investigated for the 0.1 mm Flexinol wire with length of 120 mm. Testing was performed in the elongation range between 0.25% and 1.5% in martensite phase. Tested samples were subjected to 30 stretching cycles with a movement speed of 10 mm/min. Obtained results show that the cyclic stretching of Flexinol wire reduces its electrical resistance with each stretching cycle. Moreover, it was noted that changes in Flexinol electrical resistance during cycling stretching depend on the assumed elongation and number of the already performed stretching cycles. The observed electrical resistance change decreases with each stretching cycle. Thus, the observed changes are greater during the first stretching cycles. For elongations exceeding 1%, the Flexinol electrical resistance in the first stretching cycle increases. In each subsequent cycle, electrical resistance decreases, as in the case of the smallest value of assumed elongation. In almost all tested cases (except in the case with 1.5% of assumed elongation), Flexinol electrical resistance after 30 stretching cycles was smaller than before the test.

关键词： shape memory alloy cyclic testing sensor resistance stretching Flexinol control algorithm

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A snake robot for locomotion in a pipe using trapezium-like travelling wave

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MECHANISM AND MACHINE THEORY 2021年 158卷 104221-104221页

作者： Virgala, Ivan Kelemen, Michal Prada, Erik Sukop, Marek Kot, Tomas Bobovsky, Zdenko Varga, Martin Ferencik, Peter Tech Univ Kosice Fac Mech Engn Dept Mechatron Pk Komenskeho 8 Kosice 04200 Slovakia Tech Univ Kosice Fac Mech Engn Dept Robot Kosice Slovakia VSB Tech Univ Ostrava Fac Mech Engn Dept Robot Ostrava Czech Republic

Snake robots are a suitable solution for various types of applications, especially in rough terrain or hardly accessible areas such as, for example, pipes. This article deals with a snake robot moving in a pipe using a so-called trapezium-like travelling wave. In this paper, we present a mathematical model of locomotion of the snake robot in a pipe of rectangular cross-section. Subsequently, we designed a control algorithm using a trapezium-like travelling wave. Within the control algorithm we introduced the so-called motion matrix of a trapezium-like travelling wave that contains information about the vector of generalized variables at any point of the locomotion cycle. The paper also presents a simulation model in MATLAB R2019b interfacing with CoppeliaSim V4.0.0. Furthermore, in our research we have developed an experimental snake robot with the purpose to verify the derived mathematical model, control algorithm and simulation model. Experimental results show the influence of certain parameters of the trapezium-like travelling wave on locomotion properties, such as the travelled distance or the average speed of the snake robot passing through a pipe. In the final part of this paper, experimental results are discussed and key elements of the proposed control algorithm are highlighted. (C) 2020 The Author(s). Published by Elsevier Ltd.

关键词： control algorithm Pipe Redundant Snake robot Trapezium-like travelling wave

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